1. Field of the Invention:
The invention in general relates to hollow beam structures and particularly to an arrangement for damping induced vibrational energy therein.
2. Background Information
Various types of support structures are subject to vibrational responses during operation including low frequency modes characterized by cyclic torsional and bending deformations of the structure members.
A common type of support structure is formed of hollow beam members having apertures for weight reduction or access, and if unbalanced forces or other sources of excitation are applied at frequencies close to the natural frequencies of the low order modes, unwanted vibrations can occur. Various conventional techniques of minimizing these vibrations exist and include for example a free layer damping treatment wherein a plastic tile is applied directly on the surface of the members subject to vibration. In another technique, known as constrained layer damping, a viscoelastic damping polymer film is sandwiched between the base member to be damped and an outer plate.
In the present invention, low order vibration responses are attenuated by a damping arrangement which, for a given amount of added weight, is substantially more effective than conventional damping treatments.